The effect of increased hydrostatic pressure upon the ability of normal and regenerated endothelium to deturgesce preswollen, de-epithelialized rabbit corneas was studied. Stromal deturgescence occurred as a biphasic response when hydrostatic pressure at the endothelial surface was increased above baseline values. Initially there was a rapid phase of stromal thinning which was dependent upon hydrostatic pressure nad endothelial function. This was followed by a slower phase of corneal thinning which was independent of hydrostatic pressure at the endothelial surface for pressures between 15 and 50 mm Hg. The slow phase of thinning represents the steady-state ability of the endothelium to deturgesce the stroma. Regenerated rabbit endothelium functioned similarly to normal endothelium in deturgescing the stroma. In addition, short-term increases in hydrostatic pressure at the endothelial surface did not produce ultrastructural changes in normal or regenerated corneal endothelial cells.